So basically, I think that the champions are a bit underpowered and you don't get much choice. I think they should introduce a champions home on where you can have 1 of three champions.
Firstly you can use any champion given at one time but you can only switch them for battle if they have full health. For example, If I have a archer queen but I want the Barb king i can switch for him as long as the queen is at full health.
Secondly, they can defend your yard but only the champion presently in your cage/home. For example I could have a archer queen and switch it for the barb king and then he will defend instead of the archer queen
Thirdly, because you are currently given a limit to on hero then they need to be buffed to make them strong enough to defend and attack but not to strong to be overpowered and of course they still need to die.
Most importantly they should still be upgraded again and again each to level 40 but to do this, you have to upgrade their home whilst they are in it. However this does not limit you to upgrade one champion at a time. This can be solve by when you press on the structure, you can choose which champion to upgrade which takes up one worker, but you can also upgrade another champion which takes up another worker.
This may seem confusing but it is understandable.
Finally what you all have been waiting for the different champions. They will be divided into their group and what they specialize in;
First of all is the Barbarian King. He should be made the bulkiest of all heroes and his ability should be buffed so he can summon more Barbarians roughly 2 extra for each 5th level starting at 5 barbarians. Of course because he is the strongest in terms of health and defense, he should have the slowest speed of all heroes and also weakened damage compared to his original self. He would be the best at defending due to his high health.
Second of the champions is the Archer Queen. She should be the fastest of all the champions and also deal the most attack. She does ranged damage and can attack air and ground units when defending. Her only downside is her awful health and her rubbish defense. Her health is that bad that if at an equal Barbarian King attacked her then he would surely win. Also due to her high attack, she should have low attack per second but good movement speed. Her ability should be the same as it is before with increased rate of attack.
Finally, my personal created champion should be the minion lord. His attack and his Defense is low but this is easily counteracted with his ability to fly. He is the only Champion to have this privilege but it does come at a cost. Firstly, his attack is like the Minions but rather rapid and a high attack per second. He does not do the same damage as the Archer Queen and does not have enough Health as the Barbarian king but because he can fly he as a medium movement speed also. Because he can fly means he missed out on cannons, mortars, some x-bows but not Air defenses and other defenses. His ability is that he can put all troops around him into a small rage which moves with him but the rage will not be as powerful as the barbarian Kings'. Alternatively, he could have an ability where he drops a bunch of minions as well as doing splash damage to all ground buildings in the area. The amount of minions should definitely be less due to their extra 1 person. Finally, the minion lord is probably the worst at defending due to his low health and low attack but he can attack multiple enemies quickly.
Thank you for taking the time to read this, please reply any questions and If you think supercell should add this then get commenting